Field of the Invention
The invention relates to syringes, and more particularly, relates to smart devices for capturing dosing data from syringes.
Description of the Related Art
There are multiple diseases wherein patients have an active role in disease management. Under some treatment regimens, a patient may be required to inject medicament into their body multiple times per day. For example, diabetic patients must self-inject insulin in order to control blood sugar levels. When preparing to self-inject medicament, a patient may need to take several factors into account. For example, a patient may need to keep track of previous injection dose amounts as well as the precise times at which those doses were administered in order to calculate the dose amount and time for a subsequent self-injection. Diabetic patients may need to inject insulin several times a day at varying levels. It can prove difficult for a patient to keep track of the dose amount and time of each injection event. Furthermore, after extracting insulin into a syringe, but before injection into a patient, some medicament may be lost from the syringe during “priming,” the removal of air bubbles from the syringe. This may cause the patient to incorrectly remember the amount of insulin that was originally drawn into the syringe as the injected dose amount. These issues create a possibility of error in determining dose amounts and times which are used for subsequent self-injections.
In order to remedy these issues, the prior art has focused on sensors configured to monitor and track the linear distance traveled by a syringe stopper or plunger rod, which can be used to calculate the amount of fluid present in the syringe. However, a stopper or plunger rod can undergo several linear motions prior to injection of medicament. For example, to fill a syringe with insulin, a patient first fills the syringe with an amount of air equivalent to the amount of their intended insulin dose. The patient then pressurizes an insulin vial by injecting the air into the vial. With the syringe still in the vial, the patient then turns over the syringe and vial so that the needle end of the syringe is pointed upward. The patient then aspirates the insulin from the vial into the syringe. During this process, air may be drawn into the syringe along with the insulin. To remove the air, a patient may engage in priming, which involves several steps. First, a patient orients the needle end of the syringe straight upward. This rotation allows air to rise to the top of the needle. The patient may then tap on the syringe in order to dislodge bubbles from the sidewalls of the syringe. Next, the patient can depress the plunger until all of the air bubbles are emitted from the syringe. The multiple motions of the plunger prior to injection may all be recorded and lead to erroneous measurements of the distance traveled by the plunger during injection, and consequently of the dose amount.